Gas operated automatic firearm



Dec. 3, 1940. F. N. BRGNDBY 2,223,671

GAS OPERATED AUTOMATIC FIREARM Filed April 20, 938

; succession, this gas may "cause seriousinconven ill ' Thisgascertainlyiisquite detrimental to man- 6 -1 Patented Dec. 3, 1940 a; 1cAs-oraaa'rnn AUTOMATIC FIREARM 1 n manually reloaded -'andalso ---inautomatic firearms'some gas-fromthe explodedpowder will i alwaysremaininthe barrel "af-terach shot.-'-

ually- -reloaded firearms, in" that the "reloading requires a-"comparatively "long time. In automaticiand semi-automatic arms-,,.however, in Whiclithejreloading takesplace very rapidly,only a smallfraction or a second being required, and in whicha great number of*shots 'occur'in" rapid ienc'es,-dueto the fact that it collects as sootupon the cartridgeginthe chamber and also to some extentin'themechanism. v The presentinvention" has for its'purpose 'to removethisdrawbackin automa-tic and semiautomatic firearms of -the'-gas-reloading" type, wherein some part of the gas isj'passed' throughafchannel in the barrel intoa gas'cylinder,

wherein it presses upon' a piston and puts the piston and also theejecting and reloading mechanism in operation to" perform the" ejectingand reloading after each shot The gas cylinder whenclosed-has acomparatively large volume, for instance as set forth in my U. S. PatentNo. 2,003,066, dated May 28, 1935, according to which the volume of thecylinder is suificiently large to supply the air necessary forcompleting the burning of the gases entering said cylinder. cording tothe present invention, the channel leading from the barrel to a cylinderof aforesaid type is arranged in such manner that it makes an acuteangle with the portion of the barrel located rearwardly of the point ofentry of the channel in-tothe barrel.

This relationship between the channel and barrel is known per se, butonly in firearms, wherein the gas cylinder volume was quite small ascompared with the barrel volume and wherein the an ejector effect.

said inclined position of the said channel therefore could not and wasnot intended to have the effect obtained by this invention.

By this new combination an ejector effect is obtained which causes asucking-out of the powder gas after each shot. An inclined channelconnected with a cylinder not having sufiiciently large volume will notbe able to provide This will be understoodj'from the following:

Let it be assumed thatthe distance between the inclined channel and thebarrel mouth'is 1'70 mm. and that the velocityof the projectile I is 800meters a second. This means that the projectile requires V4700 of asecond to travel through this distance and that the driving power,

47 of a second, and consequently like a hammer blow i I Let it befurther assumed that the opening of the operating mechanism requiresabout o-of a second, and that thelength of movement of the.

mechanism is 126 mm. Then the velocity of movement of the piston wouldbe 2520 mm. a

second, from which follows that the piston will move 0.535 mm. duringthe 4 of a second, during which the driving power-is acting.

-From this calculation it is evident that the volume underconsideration, when theejector eifectis to be estimated, is the cylindervolume ataclosed mechanism. a

V Any increase in volume as a result of move men-t of the piston andconsequently any increase l in the gas quantity causing theejecto'reffect is quite negligible during the short time in which the powder gasacts upon'the piston. The'in tended ejector efiect therefore is obtainedonly', if the inclined channel is combined, according'to the 1 presentinvention, with a large gas cylinder Volume; H

An embodiment of the invention is illustrated in the drawing which showstheforemost portion of a firearm'barrel. The barrel I somewhat behindthe muzzle is provided with a bore- 2, and the bore or channel .isinclined so that its axis makes an acute angle with the barrel axis. Thechannel or bore 2 continues in a correspondingly inclined channel 3rearwardly to the front end of a gas cylinder 4, which has a piston atits rear end comprising a surrounding sleeve 5 having a bottom 6. A bar!extends rearwardly from this piston for operating the breech mechanism(not shown). The present invention is not particu- 'larly concerned withthis reloading mechanism per se. constructed according to the BritishPatent No. 415,841. The drawing shows the positionof the piston when thebreech is closed as during the the the projectile has passed by the gaschannel 2, 3, will flow through the latter and into the cylinder 4,until the projectile is out of the barrel. The projectile requires lessthan of a sec- This mechanism may for instance be I,

ond to travel from the channel 2 to the muzzle, but this time isnevertheless sufiicient for the cylinder 4 to be filled with suflicientgas to cause the motion of the piston 5, 6 and the mechanism operatedthereby during the reloading.

As the projectile, as mentioned above requires an exceedingly short timefor its travel from the gas channel until it has left the muzzle, thepiston during this short time can have moved only a fraction of themovement required of it for opening the breech.

The condition existing as the projectile leaves the muzzle is that thecylinder 4 is filled with powder gas under a certain pressure. This gaspresses upon the piston 5, 6 at one end of the cylinder, while at theother end of the cylinder it flows out through the gas channel 3, 2, andon account of the inclination of the channel flows further out throughthe firearm muzzle. This outflow of the gas takes place during therearward motion of the piston 5, 6, until the sleeve 5 has cleared thecylinder 4 and the piston and cylinder are put into connection with thefresh air.

Owing to the inclined position of the channel 2 an ejector effect isobtained because the gas flowing out from the cylinder 4 draws alongwith it the powder gas which is present in the barrel l rearwardly ofchannel 2. The condition necessary for a good efiect is obviously thatthe cylinder 4 shall have a large volume and that the length of movementof the piston shall be comparative- 1y great. If the emptied cartridgecasing has been loosened and pulled somewhat out of the chamber beforethe sleeve 5 clears the cylinder 4 fresh air will be sucked through thechamber and into the barrel as a result of the abovementioned ejectoreffect. Thereby the barrel is cleaned to a still greater extent, andsimultaneously the stream of fresh air drawn through the barrel betweeneach shot will have a cooling effect upon the barrel.

Experiments have shown that all sooting of cartridge casings, thechamber and other mechanism is avoided. Furthermore the extraction ofthe empty casings is more uniform and easier than heretofore.

I claim:

1. In a firearm of the gas reloading type, in combination a barrel, acylinder, a breech-operating piston movable under the influence ofpowder gas pressure in said cylinder, said piston closing said cylinderwhen in closed breech position and opening said cylinder to theatmosphere when in open breech position, the volume of said cylinderwhen the piston is in closed breech position being about one-half thevolume of the barrel, said barrel having a lateral bore, which, where itdisembogues into the barrel, forms an acute angle with respect to theportion of the barrel axis in rear of the bore, and means providing achannel connecting said bore with said cylinder.

2. In a firearm of the gas reloading type, in combination a barrel, acylinder, a breech-operating piston movable under the influence ofpowder gas pressure in said cylinder, said piston closing said cylinderwhen in closed breech position and opening said cylinder to theatmosphere when in open breech position, said cylinder, when in closedbreech position having a large volume of the order of one-half thevolume of the barrel bore sufficient to provide the air necessary forcompleting combustion of the gases entering thereinto from the barrel soas to reduce accumulation of soot in the cylinder, means providing achannel connecting said cylinder with said bore, said channel, where itdisembogues into the bore forming an acute angle with the portion of thebore in rear of said channel so that after firing the high pressure gasin said cylinder flows through the channel into said bore and creates aforwardly directed current of air through the bore to clear the bore ofpowder gas to minimize deposit of soot in said barrel and channel and tocool the barrel.

FRIDTJOF NIELSEN BRDNDBY.

